Molded modular terminal block



Ot. 21, 1958 w. F. MARKLEY ETAL 2,857,583

MOLDED MODULAR TERMINAL BLOCK Filed Jan. 7, 1955 3 sheets-sheet `1 ATTORNEY Oct. 21, 1958 w. F. MARKLEY ETAM MOLDED MODULAR TERMINAL BLOCK 3 Sheets-Sheet 2 Filed Jan. 7, 1955 IlIIIIIIIIIIIIIIIIIIIIIII l l l l 1 l I 1 l l l 1 l l l l I I l l l l l l u l 1 l l FIG.7

INVENTORS W. F. MARKLEY M. HQETER I Il ATTORN EY Oct. 21, 1958 v w. F. MARKLEY ETAL 2,857,583

MOLDED MODULAR TERMINAL BLocK Filed Jan. 7, 1955 s sheets-sheet s 2| 22 INVENToRs A W. F. MARKLEY BY M. HAIFTER ATTOR N EY "United States Patent() l 2,857,583 i j MOLDED MODULAR BLOCK William F. Markley, Ridgewood, and Merines Haifter, Rutherford,l N. J., assignors to Thel Western Union Telegraph Companyf, New York-N.A Y., a corporation of New York Application January 7, 1955, Serial No. 480,376

8 Claims. (CL 339-198) I This invention relates to electrical terminal blocks, and more particularly to such blocksy intended for accommodating the large number of conductors` associated with communications 'equipmentwiring in a relatively small space.

Multiple-lug terminal blocks have been employed for many years inthe cross-connecting `and distributing.. frame rooms of the wire communications industry to provide a convenient and orderly means of making thenecessary masswire terminations. Such terminalblocks. are connected in two directions, that is, theentering cable or group of conductors is fastened to an array of: terminals having a certain orientation, while the leaving or other groupof conductors'is fastened to terminals ofthe same blockhaving a different orientation. :Iltis thus necessary, when-the conductors are to be fastened' to a terminal yblock which is already secured in place, for sepa-rate clearance distances lamounting toy an adequate Working space tobe provided 'adjacent to both the entering and the leaving portions'of the terminal block.

'This condition is necessitated by the conventional construction of terminal blocks wherein terminals enter through one face thereof, and passing through the block, provide connection on` a second opposed face on; the reanside of the block.

'Ifhe disadvantage of this needfor excessive; clearance `spaceV when using conventional terminal blocks is especially apparent when they are employed as a wiringrmeans in equipment contained in a housing enclosure. Space in such structures as enclosed relay racks is at a premium, and since `access to the wiring of the equipment is usually obtainable from only one side, by means of a door in the rear of the cabinet, large and consequently expensive clearances must be provided on each side of terminal blocks mounted in the center of the doorway.

-lt is therefore an object of the present invention to provide means to reduce the access space required4 for fastening input and output wires to the terminal arrays of a terminal block.

Another object of the present invention is to provide a terminal block which is more easily and quickly wired into a circuit because of the convenient access aiforded to all terminals from a single location. yStill another object of the invention is to eliminate the production of wiring mistakes by providing a terminal block having input and output terminals always symmetrically located and simultaneously visible for instant and easy checking of connections.

A further object is Ito provide such a terminal block in nesting modular form for convenient assembly as a rigid unitary structure having any desired multiple of a predetermined number of terminals.

IOther objects and advantages of the invention will appear from a considerationy of the following description thereof, taken in conjunction with the drawings, wherein- Fig. l is a front View of a terminal block constructed in accordance with the present invention;

Fig. 2 is a sectional view on the line 2-2 of Fig. 1,

2,857,583 Patented oct. 21, 195s 2 showing theconstruction of' suchra terminal block from lthe side;

Fig. 3 is a sectional view of one of theinterior constituent decks comprising Fig. 1;

Fig. 4' is a perspective view of" the deck of Fig. 3;

EFi'g.. 5v is. a perspective view of an exterior constituent deck of Fig. 1;

Fig. 6 is a perspective viewof another embodiment'of an interior constituent deck elementy of the instant invention;

Fig. Tis a perspective view yofanexterior deck element for use with the. article shown in Fig. 6;

Fig. 8 is a topview of another embodiment of an interior constituentdeck elementV of the instant invention;

Fig. 9 is a front'view of the article of Fig. y8;

Fig.. 10 is a front'view of anexterior deck element suitable for use with the elements. of Fig; 8; and

Fig. ll isa perspective view'ofa portion of a termi-nal block deck having an extended surface between the terminals thereof. f

Referring now to'jthe drawings, Fig. 1 shows a cornposi'te terminal'. block comprising upper and lower end pieces 3 ofi identical construction, being in thel` form of rectangular blocks, of insulating material, preferably molded to shape, as. seen more clearly in. Fig. 5. Consecutive numbers 'S'are moldedinrelief across the front faces of the identical Vend pieces 3, in duplicate sets of numbers,

each starting from yarr'opposite side of the' block. As seen inFig.. l, these numbers are aligned' with terminals 6 laten described,y so that pairsV of'terminals on the same level and having the same'rrumberare internally connectedtogether; A mounting hole 4'is providediiat the cent'er of each endipiece, and cut away portions 7- exf- .tendingf to 'the rear of thefsaid` Vend pieces cooperate with corresponding portionsy of the remainder of the assembly to provide; wireways f'or convenient grouping ofthelwires to be terminated, according to the level of the terminal deck to which they yare fastened. Countersunk through holes 8in the end pieces are aligned with holes 13- in: the interior deckV elements 12, seen more clearly in Fig. 4, to retain screwsV such asl 9, compressing the assembly into an immovable structure, with the aid Vof a recess. 10` which is formed in the lower surfaces of the said end pieces` to engage a corresponding tongue 16 on the adjacent assembly to form a rigid structure. End pieces 3 are shown inl greater detail in Fig. 5.

Fig. 4 is a perspective view of an interior. deckl element such las1'2 of Fig. 1, and is seen to comprise'a rectangular molded -body of insulating materialprovided with holes 13 for the `aforementioned bolts 9.V A shallow tongue 16 is yraised in the upper surface for engagement with the mating recess of adjacent sections as. indicated in Pig 2, which is a cross sectional View of Fig. 1, taken on: the line- 2 2.

Terminal pins -6-l are constructed in` pairs, andconstitute Vythe free ends -of reentrant convolutions of wires `madeI of conductive material .as seen in Fig. 3, which is afhorii zontal cross sectional'view of `Fig.V 4. Square phosphor bronze wire plated with tin has been found to be a most successful material; for the construction of these parts. These are' arranged in nested fashionto` conserve space and -the said deck element molded around them, thus. securing them in` position. It will be -observed that the shape of the said convolutions is such .as to provide secure fastening of the terminals, without any need for adhesion between the mate-rial' `of thev block and that` of the terminals, and without need for -other deformation of the wires, changes in their cross section or the provision of' anchoring means therefor;

It is thus a feature of this construction that the internal connection between corresponding terminal pins, because? the lowest possible internal ohmic resistance for the amount of metal used in its construction.

In Fig. 6 is shown an alternative construction of the interior constituent decks, .in which it is seen that the -open rectangular slots 11 are formed in theupper and lower surfaces of the deck, such that when placed in juxtaposition with the similarly slotted surface of an adjacent deck or piece, a seriesof reentrant convolutons in the form of channels of square cross section is produced, which are capable of retaining a series of suitably formed conductors in a nested array which may be separately prepared, and assembled only at such time as the decks are fastened together into a unitary terminal block assembly. Such conductors are similar to those at 6 of Fig. 3, but as stated, are not embedded in the insulating material of the deck atthe time of its manufacture, as thereshown. The wirewaysY 17 are in this case molded entire in each deck element, and identical exterior deck elements are provided for top and bottom of the terminal block, as shown in Fig. 7, in order to terminate the assembly with a suitable single set of conductor receiving grooves at each end of the block to form an integral number of levels of square grooves. By this means, it is possible to cast or mold insulating deck elements having no metallic inserts vat the time of molding, which greatly increases the'veliciency vand rapidity of the molding operation. The reentrant f feasibility of this embodiment.

Countersunk through holes 14 appropriate to this construction are provided in the end pieces of Fig.' 7 for alignment with holes 15 in the interior deck elements of Fig. 6 to retain through bolts similar to 9 of Fig. 6.

A further and preferred form of the invention utilizes an assembly constructed in general accordance with the arrangement of Fig. 1, from interior deck elements 18 of the type shown in plan in Fig. 8 and in front view in Fig. 9 having reentrant wire convolutions with free ends comprising terminals 19 molded in place. These are assembled with appropriate identical external 4elements at top and bottom, of the kind shown in front view in Fig. l0. It is seen from Fig. 8 that the insulating deck 18 has oblique anterior surfaces, placing .the terminal pins 19 in echelon, such that the forwardly extending length of each of the pins is equal and minimal. This arrangement effectively preserves the advantage of unidirectional pin orientation and consequently access to all pins from a single direction is maintained, which results in the large saving in mounting space aforementioned, and at the same time decreases the required length of the internal conductors, resulting in a substantial saving of metal required in the construction of the terminal block and also reducing the electrical resistance of the connections. In addition, the amount of insulating material required to produce a block of a given number of terminals and of given terminal spacing is thereby reduced. f

An advantage of the preferred construction shown in Figs. 8 and 9 is that because of the oblique frontal surfaces of the insulating material containing the terminals, the leakage path across the insulation between terminals is lengthened. This increased length of the leakage path is proportional to the secant of the angle of frontal obliquity, and constitutes an improvement in the important property of insulation resistance of the terminal block. Since the molded-in arrangement of the terminals obviates any surface leakage elsewhere in the structure,`

such as the leakage experienced in other types of communications circuit terminal blocks due to the collection ofv dirt and moisture in crevices communicating with the conductors, the insulation resistance of the blocks is found to remain at a relatively high value, especially after aging and the consequent accumulation of airborne dirt thereon, as compared with that of prior` forms f of insulating blocks.

Because of the molded form of the terminal blocks, it is practical to use any of a variety of moldable plastic,

substances as an insulating material such as polyester,g

epoxy, polysilane and fluorocarbon resins, all of which have a sufliciently low electrical conductivity and moisture i' absorption to render these formerly critical factors unimportant in the design of the present form of terminal block.

surface leakage distance therebetween, as shown at Z2 Obviously, such improvement is applicable i in Fig. 11. only lto the form of block of the instant invention where the conductors are embedded in insulating material, and

would be futile if practiced on prior forms of blocks having extensive shunt leakage paths between exposed conductors. f

A further advantage of the present invention is that ticularly the large amount of space takeny up by the strip.

An important advantage of the present invention lies Y Y in its adaptability for use with wire connections made Wrapped terminal connections are produced by a tool requiring` by means of the wire wrapping technique.

frontal access to the terminal, and because of the considerable size of the tool employed and the need for" manual support and guidance thereof, any divergence between the frontal directions of entering and leaving terminal banks increases greatly the access space required for wiring the terminal block. The saving made possible by the instant invention in space required for the wiring of terminals, which was previously adverted to, is in this instance multiplied because of the unusual rei` quirements involved in this special method.y of wiring.

It has been found that the volume of the cabinet en-V closing a number of the instant terminal blocks can be reduced to about 15Yto 20% less than that` of a cabinet enclosing corresponding terminal blocks of conventional construction, without sacrice of convenience or accessibility. A consequent and somewhat greater saving of cost of the cabinet and of space occupied by the cabinet is thus attained. y

Although here described in terms of speciiic illustrative examples, the concept of the present invention is capable of exempliiication in other forms, and it is therefore .in-

tended that no limitations be placed thereon except such insulating materialyhaving wireway passage portions ex-` tending rearwardly from the anterior faces thereof, Aa

plurality of nested sets of coplanar conductor return bends'k having polygonal conductor cross-sections, disposed inthe said slabs and having substantially parallel end portions protruding a terminal forming `distance beyond the Vsaid For application elsewhere than in the interconnection A' anterior faces, at least one said slab surrounding and retaining each said conductor set, a pair of congruent cover slabs for the said terminal slabs having on the anterior faces thereof duplicate sets of indicia for being identifyngly aligned with duplicate ends of the said conductors in columnar array, releasable means to retain the said slabs in fixed compressed relation, and means to mount the said terminal block.

2. A terminal block comprising a plurality of superposed rectangular terminal decks of molded electrical insulating material having opposite surfaces adapted for mating in superposition, a plurality of metallic conductors disposed in a nested pattern of graduated sized return bends in the midplane of each of the said terminal decks and having end portions of polygonal cross-section protruding therefrom comprising aligned terminals and other- Wise completely surrounded by and embedded in the said insulating material, the said terminal decks having therein surface discontinuities of predetermined character in one mating surface and corresponding inverse discontinuities in an opposite mating surface for keyed superposition of a plurality of said decks, and having complementary Wireway portions at the sides of the said surfaces for lead wire retention, upper and lower deck shaped cover plates having terminal block mounting means therein, for superposition on the said superposed terminal decks, having contiguous bi-symmetrical linear segments of indicia on the faces thereof aligned with the said terminals, and means .to compress the superposed decks and cover plates into rigid keyed relationship.

3. The article of claim 2 wherein the said polygonal cross-section is square.

4. A terminal block assembly comprising a plurality of superposed rectangular prismatic terminal slabs of molded electrical insulating material each having upper and lower surfaces for abutment grooved in nested rectangular channels to form with a mating slab square passageways having extremities facing in substantially the same direction, metallic conductors of square cross-section substantially filling the said passageways and protruding therefrom a terminal forming distance, upper and lower conforming i deck plates having lower and upper surfaces correspondingly grooved respectively, and having duplicate sets of conductor identifying indicia aligned with duplicate conductor connected terminal columns, and means to retain the said assembly compressed into a unitary block.

5. A terminal block comprising a plurality of superposed generally triangular rght prismatic terminal decks of molded electrical insulating material having opposite surfaces adapted for mating in superposition, a plurality of metallic conductors disposed in a nested pattern of graduated sized return bends in the midplane of each of the said terminal decks and having end portions of polygonal cross-section protruding from the angular frontal surfaces thereof comprising parallel terminals and other- Wise surrounded by and embedded in the said insulating material, the said terminal decks having therein surface discontinuities of predetermined character in one mating 6 surface and of complementary character in the opposite mating surface for keyed superposition of a plurality of said decks and having complementary wireway recess portions parallel to said terminals at the lateral extremities of said mating surfaces extending completely across said mating surfaces for lead wire retention, upper and lower deck shaped cover plates having terminal block mounting means, for superposition on the said superposed terminal decks and having contiguous bisymmetrical linear segments of indicia on the anterior faces thereof aligned with the said terminals, and means to compress the superposed decks and cover plates into rigid keyed relationship.

6. The article of claim 5 wherein the said polygonal cross-section is square.

7. A terminal block assembly comprising a plurality of superposed generally triangular right prismatic terminal decks of molded electrical insulating material each having '-.upper and lower surfaces for abutment grooved in nested rectangular channels to form with a mating slab square passageways having parallel terminations pointing in the same direction in symmetrical frontalfaces thereof, metallic conductors of square cross-section substantially filling the said passageways and protruding therefrom a terminal forming distance, upper and lower congruent deck plates of moldable insulating material having lower and upper surfacees correspondingly grooved respectively and having duplicate sets of discrete indicia on the frontal faces thereof aligned with duplicate, conductor connected terminal columns, and means to retain the said assembly compressed into a unitary block.

8. A terminal block assembly comprising a plurality of superposed prismatic terminal slabs of molded electrical insulating material each having upper and lower surfaces for abutment grooved in nested rectangular channels to form with a mating slab square passageways having parallel terminations pointing in the same direction, metallic conductors of square cross-section substantially filling the said passageways and protruding therefrom a terminal forming distance, upper and lower conforming deck plates having lower and upper surfaces correspondingly grooved respectively, andhavng duplicate sets of indicia aligned with duplicate conductor connected ter-A minal columns, and means to retain the said assembly compressed into a unitary block.

`References Cited in the le of this patent UNITED STATES PATENTS 

